Automatic firearm



Patented Aug. 25, 1925.

UNITED STATES PATENT OFFICE.

CARL G. SWEBILIUS, OF NEW HAVEN, CONNECTICUT, ASSIGNOR TO THE MARLIN FIREARMS CORPORATION, OF NEW HAVEN, CONNECTICUT, A CORPORATION OF DELAWARE.

AUTOMATIC FIREARM.

To all whom it may concern:

Be it known that I, CARL GUSTAF SWEBIL- IUs, a citizen of the United States, residing at New Haven, in the county of New Haven and State of Connecticut, have invented a new and useful Improvement in Automatic Firearms, of which the following is a specification.

This invention relates to firearms and pertains especially to the breech locking mechanism thereof.

It is the object of this invention to utilize the gas pressure within the barrel immediately after firing, to lock the breech mechanism in closed osition until the gas pressure has diminis ed sufficiently to allow the gun to be safely unbreeched.

This object is attained by providing a lever, one end of which, in one position of the lever, cooperates with the breech locking mechanism to maintain the latter in locking position. The opposite end of this lever is subjected to the gas pressure within the barrel immediately on the firing of the whereby the lever is effective to maintain the locking mechanism in operative position until the gas pressure has diminished sufficiently to safely permit opening the breech.

Referring now to the drawings, Fig. 1 discloses one embodiment of the invention, F1 2 discloses another embodiment thereof and Fig. 3 is a section on line 3-3 of Fig. 2.

Within the receiver 10 is reciprocatively mounted a breech-bolt 11 which is normally urged toward the forward portion of the receiver by an action spring 12 through the medium of the rod 13 and plunger 13?. A barrel 14: is carried b the front wall of the receiver and is provi ed with a plurality of sockets 15 which communicate with the interior of the barrel through the ports 16. In the receiver is pivoted a hammer 17 for the actuation of which is provided the hammer spring 18. A firing pin 19 is mounted in the breech bolt 11 in a well-known manner.

In a socket in the front wall of the receiver is pivoted a lever 20, one end of which extends under the barrel adjacent the sockets 15, and the other end of which projects into the receiver and underlies the breech bolt 11. The lever 20 is slotted to allow the magazine M to pass therethrough. In each sockis first forced downwardlfy 1 et 15 is a plunger or piston 21, the outer end of which engages the forward end of the lever 20. A spring 22 underlies the rear end of the lever 20 and maintains said end in contact with the under face of the breechbolt 11; this spring also acts to move the rear end of the bolt into locking position in the socket 11 when the bolt is in breech closing position.

A link 23 has its front end pivotally connected to the hammer 17 and has its rear end reciprocatively mounted in the hammer spring abutment 24. Near the rear end of the link 23 is a projection 25 which is adapte d when the hammer is in its cocked position, to engage the front face of the abutment 2 1, the rear end of the link being forced downwardly by the spring 26. A trigger 27 is pivoted to the bottom wall of the receiver and is so arranged that, when pulled, it disengages the projection 25 from the abutment 24. A dog 28, pivoted to the top of the trigger, engages the link 23 to lift it, and is rotatable by the projection 25 in case the trigger is in its pulled position while the gun is being reloaded after firing. This arrangement precludes the possibilitv of the gun being fired a second time until after the trigger has been released and operated a second time.

The operation of this gun is asfollows: Assume that a magazine M containing cartridges has been attached to the gun and there is no cartridge in the chamber and the elements are in the position shown in Fig. 1. The breech-bolt 11 is pulled back against the action of the spring 12, by means of the operating handle 29 on the bolt 11. In its rearward travel, the bolt against the action of the spring 22 to sengage its rear end from the socket 11 in the top wall of the receiver. As the bolt moves rearwardly, it rotates the hammer 17, thus causing the link 23 to move forwardly until the projection 25 can engage the abutment 24. If it happens that the trigger is being pulled rearwardly at this time the projection 25 will engage the dog 28 and rotate it forward sufiiciently to allow the projection to engage the face of the abutment. As the breech-bolt advances, it engages a cartridge and chambers it and as the breechbolt reaches its forward position its rear end is lifted up into the socket 11* by the spring 22. Throughout the reciprocation of the breech-bolt, the rear end of the lever has been in contact with the underface of the breech-bolt and it is lifted by the spring 22 simultaneously with the rear end of the breech bolt. The plungers 21 remain normally in contact with the forward end of the lever 20. The gun is now ready for firing. A pull on the trigger releases the hammer 17 which strikes the firing pin 19, thus exploding the cartridge. As the bullet passes the ports 16, the gas pressure within the barrel is applied against the pistons 21, thus positively holding for a short time the lever 20 in the position which it assumed under the influence of the spring 22. I/Vhile this pressure is maintained through the lever 20, the rear end of the breech-bolt is thus maintained in the socket, and the breechbolt is thus momentarily positively locked from moving rearwardly, as it would otherwise do under the influence of the gas pressure in the barrel applied to it through the cartridge shell. The arrangement and size of the ports 16, the pistons 21 and the lever 20 are such that the initial high pressure within the barrel is effective to securely prevent rearward movement of the breech-bolt while the gas pressure in the barrel is high but, when the gas pressure within the barrel has sufficiently diminished to safely allow the unbreeching of the gun, to release the locking eifect of the lever 20 and allow the breech bolt 11 to be moved rearwardly under the influence of the gas pressure within the barrel to reload the gun.

The mechanism disclosed in Fig. 2 differs from that of Fig. 1 only in that the breech-bolt is not tilted when in locking position but instead is provided with a pivoted locking member which seats in the socket 11 and a ainst the under-face of which the rear end of the lever 20 bears.

This general arrangement of locking mechanism compensates for variations in strength of charge in the ammunition. For, although there may be a variation in the initial high pressure in the gun barrel, still the resultant locking force through the lever is always sufficient to positively lock the breech-bolt against rearward movement until it is properly released by the reduction of pressure in the barrel.

It is, of course, understood that various modifications may be made in the structure and arrangement of the elements of this locking device without in any way departing from the spirit of the invention as set forth in the appended claims.

Vhat is claimed is:

1. In a firearm, a receiver, a barrel having ports, a. breech mechanism reciprocatively mounted in said receiver, a lever pivoted to a wall of said receiver, one end of said lever being adapted to cooperate with said breech mechanism to maintain it in locked position, and means for transmitting pressure from gas within the barrel to the opposit end of said lever whereby said breech mechanism is maintained in locked position.

2. In a firearm, a receiver, a breech mechanism reciprocatively mounted therein, a barrel having ports, a lever ivoted to one wall of said receiver, one end of said lever being adapted to cooperate with said breech mechanism to maintain it in locked position, a spring to move said lever and breech mechanism into locking position, and means for transmitting pressure from gas within the barrel to said lever, whereby said breech mechanism is maintained in looking position.

3. In a firearm, a receiver having a socket, a breech mechanism having a portion adapted to seat in said socket, a barrel having ports carried by said receiver, a lever pivoted to one wall of said receiver, one end of said lever underlyin said breech mechanism, a spring underlying said end of said lever, said spring being effective to lift said end of said lever, whereby said portion of said breech mechanism is seated in said socket, and means for transmitting pressure from gas within said barrel to the other end of said lever, whereby said portion of said breech mechanism is maintained in said socket.

4. In a firearm, a receiver, a breech-bolt reciprocatively mounted therein, a locking member carried by said breech bolt, a barrel carried by said receiver, a lever pivoted to said receiver, one end of said lever underlying the free end of said locking member, and means for subjecting the other end of said lever to the gas pressure within the barrel.

5. In a firearm, a receiver, a breech-bolt reciproeatively mounted therein, a lockin member carried by said breech-bolt, a barrel carried by said receiver, a lever pivoted to said receiver, one end of said lever underlying the free end of said locking member, a spring underlying said end of said lever, and means for communicating gas pressure within the barrel to the other end of said lever.

6. In a firearm, a receiver, abreech-bolt reciprocatively mounted therein, a locking member carried thereby, a barrel carried by said receiver, a lever pivoted to said receiver, one end of said lever underlying the free end of said lockin member, means for lifting said lever and Iocking member into operative position, and means for maintaining said lever and locking member in such position while the gas pressure in the barrel is high.

7. In a firearm, a receiver, a barrel carried thereby, a breech mechanism reoiprocatively mounted in said receiver, means in said receiver adapted to be engaged by said breech mechanism to prevent rearward movement thereof, means to move said mechanism into engagement with said means, and means subjected to the gas pressure within said barrel for maintaining said mechanism in said position.

8. In a firearm, a receiver, a barrel carried thereby, a breech mechanism reciprocatively mounted in said receiver, means to move said mechanism into locked position, a lever ivoted to said receiver, one end of said lever being effective to maintain said breech mechanism in locked position, and plungers mounted in said barrel and subjected to gas pressure within the barrel, said plungers being operatively related to the other end of said lever.

9. In a firearm, a receiver, a barrel carried thereby, a breech mechanism mounted in said receiver, means to move said breech mechanism into locked position, a lever pivoted in said receiver, and adapted to maintain said breech mechanism in locked position, and means for communicating to said lever the gas pressure within the barrel.

10. In a firearm, a receiver, a breech-bolt reciprocatively mounted therein, a locking member pivoted thereto, a barrel carried by said receiver, a lever pivoted to said receiver, one end of said lever underlying the free end of said locking member, means for lifting said lever and locking member into operative position, and plungers in said bar,-

rel subject to gas pressure within the barrel, said plungers being in contact with said lever, whereby gas pressure within the barrel maintains said breech mechanism in locked position.

11. In a firearm, a receiver, a breech-bolt reciprocatively mounted therein, a locking member carried by said breech-bolt, a lever pivoted to said receiver, said lever being slotted to allow the insertion of a ma azine, one end of said lever underlying sai locking member, and means for transmitting to the other end of said lever gas pressure within the barrel.

In witness whereof, I hereunto afiix my signature this 15th day of Feb. 1923.

CARL G. SWEBILIUS. 

